A contactor is a mass transfer device that removes-or adds a material to a fluid. Contactors may be used to remove or add gas to a fluid stream. Hollow fiber membrane contactors are known. For example, see U.S. Pat. Nos. 3,288,877; 3,755,034; 4,220,535; 4,664,681; 4,940,617; 5,186,832; 5,264,171; 5,284,584; and 5,449,457. Hollow fiber membrane contactors are commercially available under the name of LIQUI-CEL® from Celgard Inc. of Charlotte, N.C. and under the name of SEPAREL® from Dianippon Ink and Chemicals of Tokyo, Japan. Such contactors have numerous uses, one being the degassing of liquids.
To facilitate manufacture of these contactors, the hollow fiber membranes are typically formed into a fabric (e.g., woven or knitted). The fabric could be wound around a mandrel (e.g., a perforated center tube) and fixed into place by potting the fabric edges, with either thermosetting or thermoplastic materials, to form a unitized structure. See, for example, U.S. Pat. Nos. 4,940,617 and 5,284,584. This unit can then be inserted within a shell and sealed, i.e., with or without O-rings, to make a membrane contactor. See, for example, U.S. Pat. No. 6,207,053. However, because of potting shrinkage and/or expansion, it is difficult to maintain the seal between the unit and the shell in membrane contactors with large diameters.
Most hollow fiber membrane contactors with small diameters are made by integrally potting the unit inside the housing. This eliminates the need to provide or maintain any additional seal therebetween the unit and the housing via other means, i.e. O-rings, or gaskets. As the contactor diameter becomes large, however, it becomes more difficult to maintain the joint between the unit and the housing due to many possible reasons such as shrinkage or expansion of either the cartridge or the unit during or after potting. Thus, instead of integral potting, elastomeric O-rings have been used to create a seal therebetween the unit and the housing, but as contactor diameter becomes large, O-ring seals also become difficult to maintain and/or rectify uniformly.
Accordingly, there is a need for a membrane contactor with a large diameter, where the unit could be secured inside the housing permanently by employing a more robust potting method that lends itself to high mechanical strength and durability; furthermore, there is a need for a method of making the same.